The present invention relates to a vacuum valve for die casing machine, especially to a vacuum valve for die casing machine, which has an improved structure to prevent the congestion problem of valve hole.
FIG. 1 shows a prior art vacuum valve for die casing machine, which comprises a vacuum valve seat 1 and a movable stage 2. The vacuum valve seat 1 comprises an induction rod 11 and a control rod 12. The induction rod 11 and the control rod 12 are arranged in the vacuum valve seat 1 and have tooth racks 13 and 14 respectively and oppositely. A pair of gears 15 and 16 is provided between the tooth racks 13 and 14 and pivotally arranged within a tank 10 in the vacuum valve seat 1.
The induction rod 11 and the control rod 12 have synchronous movement due to the linkage of the gears 15 and 16. The vacuum valve is connected to a molding die (not shown) and may inhale the molten metal. The vacuum valve is functioned to drain air out of the molding die to facilitate the molten metal to flow into the air-exhausted molding die. Otherwise, remaining air in the molding die may cause defect therein.
Therefore, the vacuum valve is functioned to both suck air from the molding die and speed the molten metal to flow into the air-exhausted molding die. The induction rod 11 and the control rod 12 are linked to each other and simultaneously seal an induction hole 17 and a valve hole 18 in the vacuum valve seat I when the molding die is full of molten metal, thus sealing a ventilating path 41 connected to a ventilator 4. At this time, the molten metal is flown from the molding die to the vacuum valve and fill a reserved space 19 in the vacuum valve seat 1.
As shown in this figure, the valve hole 18 is provided with respect to the control rod 12, wherein the valve hole 18 is a tunnel-shaped hole and the control rod 12 has a conic distal end 121. When foreign object is present in the valve hole 18, it is hard for the conic distal end 121 to seal the valve hole 18. Therefore, the vacuum valve is still ventilated by the ventilator 4 and the ventilator 4 even may inhale the molten metal. The ventilator 4 has the risk of being deteriorated by the foreign object and post-cleaning of the ventilator 4 is cumbersome.
It is the object of the present invention to provide a vacuum valve for die casing machine, which has an improved structure to prevent the congestion problem of valve hole. More particularly, the vacuum valve has a control rod with plurality of axial slots on one end thereof. The axial slots can advantageously remove foreign object from the valve.
To achieve above object, the present invention provides a vacuum valve for die casing machine comprising a valve seat, a bottom die and a top die. A wavy lead-in runner is provided between the bottom die and the top die. The bottom die has a vent hole and the top die has a feed-in inlet. The valve seat has a plurality of positioning pins engaged with corresponding positioning holes on the bottom die. The valve seat has an accommodating tank enclosing a pair of gears and each gear engaged with one tooth rack. An induction rod is arranged on the tooth rack near the feed-in inlet and passing through an induction hole on the bottom die. A control rod is arranged on the tooth rack near the vent hole and passes through a valve hole on the bottom die. The control rod has a plurality of axial slots on one end thereof. The axial slots are initially exposed out of the valve hole and moved with the control rod to indent into the valve hole to seal the valve hole.